1 We have reviewed the clinical features and management of 44 consecutive patients presenting to hospital over a 5 week period during an outbreak of ingestion of psilocybin containing mushrooms. 2 Patients presented to hospital usually because of dysphoric effects an average of 3.8 h after ingesting mushrooms. 3 Mydriasis was present in 40 patients but fewer than half showed other sympathomimetic features--tachycardia, hypertension or hyperreflexia. 4 Twenty-three patients experienced nausea and vomiting. 5 Distortions of perception chiefly visual were frequent as were paraesthesiae and feelings of depersonalization. 6 The effects of the mushrooms were short-lived and had worn off within 12 h in all but one patient. 7 Inducing emesis did not appear to hasten recovery from the effects of the mushrooms.